Metallic coating and process of making same.



' M. U. SCHOOP.

METALLIC COATING AND PROCESS 'OF MAKING SAME.

APPLICATION FILED NOV. I4, I914- Patented Apr. 18,1916.

UNITED STATES OFFICE."

MAX ULRICH SCHOOP, OE HONGG, NEAR ZURICH, SWITZERLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 METALS COATING COMPANY OF AMERICA, OF BOSTON, MASSA- CHUSETTS, A CORPORATION OF MASSACHUSETTS.

METALLIC COATING AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Apr. 18, 1916.

Original. application filed April 1, 1910, Serial No. 552,800. Divided and this'applieation filed November 14, 1914. Serial No. 872,168.

To all whom it may concern:

Be it known that I, MAX ULnIoH SGHOOP, a citizen of the Republic of Swltzerland, re-

siding at Hongg, near Zurich, Switzerland,

have invented certain new and useful Improvements in Metallic Coatings and Processes of Making Same.

My invention relates to homogeneous metal layers or coatings formed on articles of various kinds and the process of making same, which coatings may be extremely .tenaci ous,'or capable of being removed.

atomizing the metal. This agent maybe;

either high pressure steam, hot compressed air, or any other gas or vapor under sufficient pressure to atomize the metal in a suitable atomizer, whether heated or not.

4 Instead of atomizing the metal, the liquid metal may be projected onto the surface to be coated in a very fine or capillary stream, or a number of streams united to form a spray, there being used for the purpose one or more nozzles of suitableform through which the molten metal is forced. In some cases I have forced a continuous fine stream of metal from a nozzle and broken the continuity of" the stream by rapidly vibrating the nozzle, or a stream of metal may be directed against an inclined plate and thus sprayed.

The subdivision of the liquid metal can also be accomplished in a mechanical way by a suitable centrifugal machine, and, finally, a large number of -metals may be projected and atomized in a molten state in an apparatus similar in structure to the atomizcrs used in medicine. The metal in this device is projected or forced from the bath in a fine continuous stream or thread,

and then coming into contact with the issuing air or gas is immediately atomized.

The pressure medium used for atomizing may be either neutral, in so far as the metal is concerned, or it may have a chemical action on the metal as it is atomized, which chemical action may be either oxidizing or reducing. p I

Thepressure, during the atomization and projection, may be indicated by any suitable device, such as the pressure gages which I have shown in the drawings and hereinafter, described.

It is immaterial how the liquid metal is atomized, or whetherthe apparatus used for the subdividing the metal as described is stationary or transportable, as the fundamental idea consists in-producing-metallic coatings of any desired thickness by projecting liquid metal in a finely dividedstate onto a suitable article or base, said coatings being non-porous, uniform, homogeneous, and of good appearance.

If it is important to obtain a coating entirely free, or almost entirely free, from oxid, and in case the subdivided or atomized metal has a tendency to oxidize, then itis necessary to use an inert gas as a pressure and atomizing medium. Such la result is, however, notalwaysdesired. On the other hand, under certain circumstances it may be advisable to use a gas or vapor having a strong chemical or oxidizing action, thereby obtaining coatings having a more or less predominant metallic appearance, according to the degree of oxidation. However, the same result can be obtained by producing an unoxidized metallic coating in the manner set forth, and subsequently oxidizing the same in an oxidizing atmosphere in a closed chamber, or otherwise.

By suitably selecting orv dimensioning the atomizing apparatus, the atomized metal can be sub-divided so extremely fine that it resembles a cloud, so that when the articles 'to be coated is brought into the same there results a surface coating having a beautiful, smooth metallic luster. The metallic microscopic globules or drops 9f this metallic cloud, on account of their great speed, due to the liquid metal being under pressure. are projected with great force from the atomizing nozzle.- These globules are fiattened out and formed into very thin scales that lie adjacent to and overlap one another,

-so that th ey are welded together, which results in an'intimately connected metallic sheet, or coherent metalhc body, whose structure is very dense and tough. This coating may be composed of a mixture of metals, by using a moltenv mixture which is atomized and projected onto the body or article to be coated; Fluxes may be used, and added to the metal in'the melting pot, and the flux may be such' that it is vaporized and produces the vapor that gives the required pressu'reyfor the atomization of the molten metal. Admixtures of metals may be used. Various vapors or gases may be used to produce the atomization of the metal at the atomizing nozzle whose chemical action on the metal will change the appearance of' the coating. The structure and chemical character of the finished metal coating is, therefore," dependent'upon .the manner in which it is produced, and must be varied according to the effect to be achieved.

The melting pointbof the metal of the coating, the character and temperature of the surface to be coated, the pressure used in atomized and the thickness to be attained, as Well as the distance of the nozzle from the object to be'coated, will more or less influence the character of the coatings to be made aswell as the manner in which the coatings are made-1st Nearly all metals are sufliciently fluid at suitable temperature to producefine subdivision inaccordance withi' this invention,-

possible to produce durable aluminum articles in a practical manner, or to coat metallie articles with aluminum, which'heretofore not been possible electrolytically.

It is obvious that alloys of metals may be used instead of substantially pure metals.

I will now describe how I make separable or removable metal coatings, for the reproduction of printing clichs, medals, etc. In order to produce these removable coatings, it is necessary or advisable to oil or grease the matrix or base, or coat it. with graphite, or treat it in any other wellknown manner for the purpose of preventing the adhesion of the metallic coating; and in some cases it is desirable to keep the matrix heated during the application ofthe metallic "coating, but this may be dispensed with in the majority of cases where the coating to beapplied is not extraordinarily thick.

In order to make a comparatively thick coating, and thereby a coating readily separable from its base, the time, during which the surface from which the impression is to be taken is exposedto the atomized or finely the atomized metal for about ten seconds.

After the metallic coating has been formed on the matrix as above described, the

matrix may be dropped into cold water to quicklyshrink it, and thereby'readily re-.

lease it from the articles made.

In certam cases 1t 1s--qu1 readily removed from their bases, for example, for the production of metallic foil; and in some-instances it is advisable to have te possible to make extremely thin metal sheets, that are the matrix or base as smooth as possible, in

order to more readily release the metal. coating after it has been formed.

Metallic sheets or foils which have been formed-on polished or cut glass in the manner described, will adhere to these onlyby the action of atmospheric pressure, and remind one in their structure and general appearance of the photographic transfers made on polished glass, and' have a very high luster.

By my method, it is possible to quickly and cheaply reproduce matrices and printing blocks of all kinds, medallions and the like, which has heretofore beendone by electrolytic methods. In ten hours, with the same negative matrix, from three hundred to four hundred reproductions can be made, which are as sharp and fine in every detail, and as beautiful in their appearance as electrieally plated reproductions. The metallic particles are thrown with great force, compared to their size, onto the matrix or support, and are cemented or welded together into a compact metallic sheet forming a coherent metallic body.

A further advantage of my new process.

consists in that the electrolytic bath is entirely avoided, sothat bodies of any desired shape and size may be reproduced, hollow bodies being made in parts which are afterward soldered together, and any metal whatever may be used to reproduce these articles, so that aluminum and other metals can beus ed, which cannot readily be done in an electrolytic bath.

hollow vessels, and to this end a core of suitable material is placed in the-metallic cloud and rotated, or the atomizer may be moved around the core or base to be covered, after which the core iseither physically or chemi- Further, it is readily pos 'sible to make seamless .metallic tubes. .or

callv removed by meltin or burnin it out or by removing it by acids. The thickness of these'removable metal coatings may be varied within comparatively wide limits, and the thickness obtained within a definite time will depend upon the gas pressure used for atomizing or subdividing the liquid metal, and upon the gas itself, whether oxidizing, reducing or neutral. The distance the object is held from the atomizing nozzle, as well as the size of the openings in said atomizing nozzle, are also factors upon which the thickness depends.

The density of the particles of coating is dependent upon the distance the article is held from the atomizing nozzle, as the shorter the distance the less time the atomized particles have to cool or set, or to become oxidized.

If the pressure medium used for atomizing the fluid metal is neutral, then there is practically no difference whatever in the metallic coating formed and the general character of the metal. If the pressure medium is capable of oxidizing the metal, then the coating contains more or less oxid and is more or less porous, so that there will be a limitation to the thickness to which said coating can be'made.

A peculiarity of the metallic cloud, or atomized metal, is that in general its temperature is very low, and the finer the atomization the lower the temperature, and of course the finer the atomizing the greater will have to be the gas pressure used to produce it, so that materials maybe used as matrices whose melting and ignition temperatures are very low, for example, such materials as hard paper and celluloid. It is also possible to hold the naked hand in the metallic cloud without injury, or without feeling any pain, which shows that the most delicate tissues can be reproduced.

The temperature may be varied within wide limits as circumstances demand or permit. I-have used the process in cases where the temperature of the metallic cloud was in the neighborhood of 60 Celsius, and also in cases where the temperature was increased to 5200 Celsius and more. Figures 1 and 2 taken together show, by way of example, one form of apparatus suitable for carrying out'my invention, being partly in section and partly in elevation.

In the particular form of apparatus illustrated, a, a, are the steel flasks containing compressed gas, for example, air.. These flasks are connected to a coil 0 contained in a suitable casing 0 provided with a gas burner d for heating the coil and the air therein which has become cold by reason of expansion. The metal 7 is contained in a preferably, but not necessarily, closed melting pot 2' provided with a valve h controlling the outlet to the pipe on which terminates in a downwardly directed nozzle 9.

The heating coil 0 has two branches, one

entering the pot i above the level of the metal f and the other 1 terminating adjacent 1. The process of producing a separable 4 metallic body, which consists in coating :1. form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat and pressure, and substantially at the same time projecting said sub-divisions against said coated form. while keeping said form heated during said pr0 jecting, with suflicient force to produce a homogeneous non-porous body upon said form, and finally separating said metallic body so produced from said form.

2. The process of producing a separable metallic body, which consists in coating a form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat and a gaseous pressure medium having a reducing action on the metal, and substantially at the same time projecting said sub-divisions against said coated form, While keeping said form heated during said projecting, with suificient force to produce a homogeneous non-porous body upon said form, and finally separating said metallic body so produced from said form.

3. The process of producing a separable metallic body, which consists in coating aform with a non-adhesive substance, then finely sub-dividing a metal underthe combined action of heat and a gaseous pressure medium having a chemical action on the metal, and substantially at the same time projecting said sub-divisions against said coated form, while keeping said form heated during said projecting, with sufficient force to produce a homogeneous non-porous body upon said form, and finally separating said metallic body so produced from said form.

4. The process of producing a separable metallic body, which consists in coating a form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat and pressure, and substantially at the same time projecting said sub-divisions against said coated form with suflicient force to produce a homogeneous non-porous body upon said form, and then shrinking said form to separate said metallic body so produced from said form.

5. The process of producing a separable metallic body, which consists in coating 2. form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat and a gaseous pressure medium having a reducing action on the metal, and substantially at the same time projecting said subdivisions against said coated. form with suflicient force to produce a homogeneous non-porous body upon said form, and then shrinking said form to separate vsaid metallic body so produced from said form.

- 6. The process of producing a separable metallic body, which consists in coating a form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat andv a gaseous pressure medium having a chemical action on the metal, and substantially at the same time projecting said sub-divisions against said 15 form with a non-adhesive substance, then finely sub-dividing a metal under the combined action of heat and pressure, and sub- 'sta'ntially at the sametim prOiecting said sub-divisions, while exerting a chemical ac tion thereon, against said coated form, while keeping said form heatedduriiig' said projecting, with sufficient force to' produce a homogeneous non-porous body upon said form, and finally separating said metallic body so produced from said form.

8. The process of producing a separable metallic body, which consists in coating a form with a non-adhesive substance, then finely sub-dividing a {metal under the combined action of heat and pressure, and substantially at the same time-projecting said sub-divisions, while exerting a chemical action thereon, against said coated form with sufficient force to produce a homogeneous non-porous body upon said form, and then" shrinking said form to separate said metallic body so produced from said form.

Witnesses: i

CARL GUBLER,

A GUST Rm'iee.

- MAX ULRICH soHooR 

